Fix python scripts in src/tools/

tools/valgrind/memcheck_analyze.py

-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # memcheck_analyze.py
 
 ''' Given a valgrind XML file, parses errors and uniques them.'''
 
 import gdb_helper
 
@@ skipping 587 matching lines @@
                                   key=lambda (k,v): (v,k)):
         logging.info("%7d %s" % (count, name))
       retcode = -3
 
     if retcode != 0:
       return retcode
 
     logging.info("PASS! No errors found!")
     return 0
 
+
 def _main():
   '''For testing only. The MemcheckAnalyzer class should be imported instead.'''
-  retcode = 0
   parser = optparse.OptionParser("usage: %prog [options] <files to analyze>")
   parser.add_option("", "--source_dir",
                     help="path to top of source tree for this build"
                     "(used to normalize source paths in baseline)")
 
   (options, args) = parser.parse_args()
   if len(args) == 0:
     parser.error("no filename specified")
   filenames = args
 
   analyzer = MemcheckAnalyzer(options.source_dir, use_gdb=True)
-  retcode = analyzer.Report(filenames, None)
+  return analyzer.Report(filenames, None)
 
-  sys.exit(retcode)
 
 if __name__ == "__main__":
-  _main()
+  sys.exit(_main())